Bromine → Isoxazole, 3-[3-bromo-2-methyl-6-(methylthio)phenyl]-4,5-dihydro-

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反応手順

At 0° C., 10 g (48 mmol) of 3-(2-methyl-6-methylthiophenyl)-4,5-dihydroisoxazole are added a little at a time to 120 ml of conc. sulfuric acid, and the mixture is stirred for approximately 30 minutes. 3.7 g (23 mmol) of bromine are then added dropwise, and the mixture is stirred at 0° C. for 2.5 hours. Over a period of approximately 45 minutes, the mixture is subsequently allowed to warm to room temperature. A homogeneous solution forms. For work-up, the reaction mixture is poured into ice-water and extracted three times with methylene chloride. The organic phase is washed with sodium bicarbonate solution, dried with magnesium sulfate and concentrated. This gives 11.4 g of crude product which is employed in the next step without any further purification.

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